Projection system



y 2, 1967 E. F. PERLOWSKI, JR 3,317,665

PROJECTION SYSTEM Filed Aug. 26, 1964 FIG.I

35 SCREEN ELECTRON GUN INVENTORZ EDWARD F. PERLOWSKI,JR.

HIS ATTORNEY.

United States Patent .York

Filed Aug. 26, 1964, Ser. No. 392,110 11 Claims. (Cl. 1787.5)

This invention relates to projection systems of the electronic type. More particularly, it relates to such pr ojection systems having a container with a conducting mterior and a deformable medium in the container that decreases in resistivity with decreases in thickness in th presence of an electrical charge on the surface of the medium, the medium being the polymeric reaction product of benzyl chloride and biphenyl material.

There is described in US. Patent 2,943,147, June 28, 1960, assigned to the same assignee as the present invention, a projection system of the above type employing a deformable medium having a high resistivity which is responsive to a velocity modulated electron beam. Generally speaking, this projection system, which is illustrated in FIG. 1 of the drawing, comprises an evacuated glass envelope containing an electron gun 11 for producing an electron beam 13 deflecting the beam in a rectangular raster over the surface of a light transmitting deformable medium 15 which is within a portion 17 of the transparent container. An enlarged view of this portion of the assembly is shown in FIG. 2. The beam 13 is preferably velocity-modulated by a television signal applied to the deflection means (not shown) in the electron gun 11. Deformable medium 15 has a central portion 19 of decreased thickness which is coincident with the raster area of beam 13 produced by electrons from beam 13 which are attracted to a conducting coating 21 on the inner surface of the container portion 17. These same electrons also produce deformations in the surface of the deformable medium 15 and the amplitudes of these deformations are a function of the number of electrons deposited by the beam 13 at the various points on the surface of medium 15. Thus, the amplitudes of these deformations are a function of the modulated electron beam 13.

The deformations on the surface of medium 15 are utilized to diffract light from a source 23 in an optical system including a lens 24 which projects an image of light source 23 on the surface of medium 15 through a bar and slit system 25. Another lens 29 images the slits of system on the bars of another bar and slit system 31 if there are no deformations on the surface of deformable medium 15. However, any deformations on such surface diffract the transient light so that it passes through the slits in the system 31 with an intensity that corresponds to the amplitudes of the deformations and hence the amplitudes of the applied modulating signal such as a television signal. The light passing through system 29 is imaged by a projection lens 33 on screen 35 by means of mirror 37.

If a conventional deformable medium is utilized at 15 in the illustrated system, the average charge density produces a force on the medium 15 that overcomes the surface tension from the excess medium outside the raster area and decreases the portion 19 of medium 15 to zero thickness. Under such conditions, no deformations can be formed and the system becomes inoperative until the medium is replaced. The above patent teaches that if the medium has the property of decreasing in resistivity with decreasing thickness, portion 19 does not decrease to zero thickness under the pressure of the charges but maintains a thickness which is a function of the magnitude of charge density on the surface of the medium 15. With decrease in resistivity, the time constant is decreased for the passage of leakage current from 3,317,665 Patented May 2, 1967 ice the surface of deformable medium 15 to the conducting coating beneath it. This results in an increase in leakage current, decreasing the charge density on the surface of the medium 15 and somewhat relieving the pressure. Eventually, an equilibrium condition is reached in which the pressure from the charges on the surface of the medium equals the pressure from the surface tension on the excess medium surrounding the raster at which the thickness at this equilibrium condition is maintained. The charge density on the surface of the medium never decreases to zero because of such leakage because it is continually being replaced by electrons from beam 13.

The deformable compositions described in the aforesaid patent, US. 2,943,147, as suitable for the medium are required to be transparent, be capable of withstanding electron bombardment without significant decomposition, have a viscosity at the operating temperature (between about 25 C. and 150 C.) of approximately to 50,000 centistokes, and the deformable composition must not decompose the conducting coating. The medium must also have a volume resistivity that varies Within the range of approximately 10 to 10 ohms-cm., with the average resistivity at the stable thickness preferably being approximately 10 ohms-cm.

Among the deformable media or fluids described in this patent are, for instance, beeswax, methyl silcione fluids, methyl silicone fluids containing up to 5% of phenyl silicones, methylphenyl silicones containing an average of two methyl and phenyl groups per silicon atom in which the mole ratio of methyl groups to silicon atoms is greater than 0 and less than 2, etc. However, it has been found that these deformable fluids are not as stable as one would desire because under the influence of an electron beam, the deformable medium or deformable fluid tends to increase in viscosity and with continued use of the projection system described above, the viscosity increases to a point where gel particles begin to form and ultimately the deformable medium gels. This means that the ap paratus can no longer be used with that particular deformable medium.

It will be evident from the above that there is a continuing need for materials which can be used as medium 15 which are charactedized by a desirably low rate of thickening under the radiation effects of electrons from beam 13. At the same time such materials should be characterized by good writing behavior under the action of electrons. They should have a good general working viscosity and small decrease in fluidity and use. They should have a low vapor pressure and yield very little gas electronic bombardment. They should also be characterized by suitably high electrical resistivity and should be economical to use.

It is a primary object of this invention to provide materials which are possessed of such desirable qualities and a projection system of the above type which utilizes these qualities.

It has been found that the polymeric Friedel-Crafts reaction products of chloroalkylated aromatic materials, such as benzyl chloride with biphenyl, fit the above characteristics and provide a deformable medium which is possessed of long working life. Methyl-substituted biphenyl is also useful as are aromatic-substituted biphenyl and aralkyl-substituted biphenyl such as the benzyl and napthyl-substituted material. Mixtures of these materials are also useful. Generally speaking, the useful materials have a viscosity of at least 100 centistokes (cs.) at 25 C. and have the other desirable qualities which have been found to be useful.

Benzyl chloride is the preferred chloroalkylated mate rial used herein. It will, of course, be appreciated that other halo-substituted benzyl materials of the above description can be used such as the iodoand bromo-substi- 3 tuted materials. However, the chloro-substituted materials are preferred from the point of view of cost and ready availability as well as from the point of view of easier processing.

Aluminum chloride is preferred as the catalyst material but other Lewis acid materials well known to those skilled in the art, including zinc chloride, ferric chloride, boron trifluoride, mercury zinc amalgam, mercury sodium amalgam as well as various silicate materials, can be used.

Generally speaking, in forming the present materials, preferably from about 0.8 to 3 moles of chloromethylated aromatic material, such as benzyl chloride, are used for each mole of aromatic hydrocarbon and most preferably at least about one mole of halogenated material for each mole of aromatic hydrocarbon. Broadly speaking, from about 0.1 to about 10 moles of chloromethylated material is used for each mole of aromatic hydrocarbon.

The following examples illustrate the practice of the present invention, it being appreciated that they are not to be taken as limiting in any way.

EXAMPLE 1 To a solution of 308 grams (2 moles) of biphenyl in 500 cc. dry cyclohexane heated to a temperature of 35 C. there was added 2 grams of anhydrous aluminum chloride catalyst. The mixture was stirred and at a temperature of 30 C. addition of 308 grams (2.44 moles) benzyl chloride was commenced and continued gradually over a period of about one hour while cooling the reaction mixture at about 12 C. A second addition of 1 gram of the aluminum chloride catalyst was made to insure completion of reaction and the mixture stirred for 30 minutes with warming to a temperature of about 23 C. The reaction mixture was neutralized with dilute hydrochloric acid, washed with a solution of potassium hydroxide, treated with anhydrous potassium carbonate to dry the solution and further treated with Celkate to adsorb impurities. Celkate is a synthetic magnesium silicate material made by the Johns-Manville Corporation. The filtrate was dlstilled to give the following cuts or fractions:

Fraction Boiling Point M 01 N 0. Identity Range, C. Percent (mm. Hg) Yield Cyelohexane (Solvent) 80-90 (760) Biphenyl (Unreacted) 130-195 (10)...

Benzyl Biphenyl 197-280 (10) 33.2

Di-, lri-, and Tetra-Benzyl 190-358 (.06) 58.

Biphenyl. Pot Residue Over 360 (.06) 7. 6

Fraction 4 above was redistilled to yield a transparent fluid having a refractive index of 1.6456 (24 C.), a boiling range of 221310 C. at 0.004 mm. Hg, a viscosity at 50 C. of 425 centistokes and at 25 C. a viscosity of 20,580 centistokes. The resistivity was about 2.6 ohm-cm. at 50 C. and the vpaor pressure at 50 C. was 7X10 Torr. This fraction 4 was subjected to electron irradiation with a 1500 kv. resonant transformer at a current input of 200-500 microamperes at a dose of x10 roentgens/minute to a total dose of 800 megaroentgens. The total number of molecules of gas adsorbed per 100 electron volts was 0.022. This gas consisted mostly of hydrogen which can be readily pumped from the system. The increase in viscosity was about 3.5 mm./ 800 mr. This very low gas value obtained is about A that obtained with a polybenzyl toluene material. This low gas value and the very small change in viscosity show conclusively the eminent suitability of these compositions as a deformable medium in a projection system of the present type. When such a composition was used in the system, clear images were obtained.

EXAMPLE 2 To a stirred mixture of 100 grams (.65 mole) biphenyl, 300 cc. cyclohexane and 2 grams of aluminum chloride there was added a solution of 350 grams (1.62 moles) of biphenyl and 455 grams (3.6 moles) of distilled benzyl chloride, the addition taking place over a period of about 2 /3 hours at a reaction temperature of 0 to 22 C. during which time large amounts of hydrogen chloride gas were evolved. An additional one gram of aluminum chloride catalyst was added to insure completeness of the reaction. The catalyst was neutralized with dilute hydrochloric acid. After washing the reaction mixture with hot caustic, the organic layer was dried with a potassium carbonate drying agent and Celkate and filtered. Solvents were removed and the residue, when distilled, produced the following fractions:

Fraction Boiling Point Mol No. Identity Range, C. Percent;

(mm. Hg) Yield 1 Unreacted Biphenyl 73-104 (10) 2 Benzyl Biphenyl 173-202 (10) 23.0 3 Di, Tri-, 'Ietra-Benzyl 190-297 (.04) 31. 5

Biphenyl. Pot Residue 300 (0.05) 31.0

Fraction 3 can be used as the transparent deformable medium in a projection system of the type described.

EXAMPLE 3 There was added to 924 grains (6 moles) of dry biphenyl in 500 cc. of dry cyclohexane containing 8 grams of aluminum chloride 926 grams (7.3 moles) of dry benzyl chloride, the addition taking place with stirring over a two-hour period, the initial temperature being 35 C. which was gradually lowered to about 12 C. during the addition process. One gram of aluminum chloride was added to assure completion of the reaction. The reaction product was treated as in Example 1 and upon distillation gave the following fractions:

Fraction Boiling Point 1101 No. Identity Range, C. Percent (mm. Hg) Yiel 1 Cyelohexane (Solvent) -90 (760) Bipl1enyl(Unreaeted) T0184 (10). Benzyl Biphenyl 187-292 (10). 4 Di, Tri-, and Tetra-benzyl 101-360 (.001

Biphenyl. Pet Residue Over 360 (.001) 15. 4

Fraction 4 above was further treated to obtain a transparent material having a boiling range of 183 C. to 276 C. at a vapor pressure of 2 10 Torr, a refractive index at 25 C. of 1.6454, a viscosity at 50 C. of 1292 centistokes, and the vapor pressure was 7 10- Torr at 50 C. This material can be used as a deformable medium in the present type of projection system.

There are provided, then, by the present invention media which because of their desirable transparency viscosity, resistance to decomposition under electronic bombardment, good resistivity, low vapor pressure and compatibility with other elements of the projection system are admirably suited for the use described. It will be realized that obvious modifications of the invention may be made without departing from the spirit and scope thereof.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A projection system comprising a container having a conducting interior, a deformable medium in said cont-ainer comprising the Friedel-Crafts reaction product of from about 0.1 to 10 moles of halogenated, alkylated aromatic and one mole of a material selected from the group consisting of bipheny-l, methyl-substituted biphenyl, aralkyl-subst-ituted biphenyl, aromatic-substituted biphenyl and mixtures thereof, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

2. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0. 8 to 3 moles of halogenated, alkylated aromatic and one mole of a material selected from the group consisting of biphenyl, methyl-substituted biphenyl, aralkyl-substituted biphenyl, aromatic-substituted biphenyl and mixtures thereof, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

3. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of at least one mole of halogenated, alkylated aromatic and one mole of a material selected from the group consisting of biphenyl, methyl-substituted biphenyl, aralkyl-substituted biphenyl, aromatic-substituted biphenyl and mixtures thereof, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating With said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

4. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0.1 to 10 moles of benzyl chloride and one mole of a material selected from the group consisting of biphenyl, methyl-substituted biphenyl, aralkyl-subs-tituted biphenyl, aromatic-substituted biphenyl and mixtures thereof, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

5. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0.1 to 10 moles of benzyl chloride and one mole of methyl-substituted biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

6. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the FriedelCrafts reaction product of from about 0.1 to 10 moles of benzyl chloride and one mole of aralkyl-substituted biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

7. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0.1 to 10 moles of benzyl chloride and one mole of aromatic-substituted biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

8. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0.1 to 10 moles of benzyl chloride and biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

9. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of from about 0.8 to 3 moles of benzyl chloride and one mole of biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

10. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-Crafts reaction product of at least one mole of benzyl chloride and one mole of biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

11. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising the Friedel-C-rafts reaction product of benzyl chloride and biphenyl, electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

No references cited.

DAVID G. REDIN'BA-UGH, Primary Examiner.

J. A,- OR Q, A s tant Exa iner. 

11. A PROJECTION SYSTEM COMPRISING A CONTAINER HAVING A CONDUCTING INTERIOR, A DEFORMABLE MEDIUM IN SAID CONTAINER COMPRISING THE FRIEDEL-CRAFTS REACTION PRODUCT OF BENZYL CHLORIDE AND BIPHENYL, ELECTRON BEAM MEANS FOR PRODUCING AN ELECTRICAL CHARGE ON THE SURFACE OF SAID DEFORMABLE MEDIUM AS A FUNCTION OF AN APPLIED ELECTRICAL SIGNAL AND COOPERATING WITH SAID CONDUCTING INTERIOR TO 